Construction workers risked having their pay docked for protesting against the Baillieu Government's tough new anti-union regulations for the building industry

More than 1,000 workers walked off building sites on Wednesday in protest against the controversial code.

The code will force companies building major public projects to sign up to the rules, which limit the powers of unions on construction sites.

Unions say the move is a "provocation".

Brian Boyd from Trades Hall says the new rules are unnecessary.

"We hope the public will understand why building unions are going through the streets," he said.

"We've already negotiated our EBA's, unlike some of the public sector unions, they're already out of the way for the next few years, yet we've got a code that's aimed at cutting wages and conditions."

Mr Boyd says federal laws are already in place to tackle illegal strikes and union actions.

He says the protest was just the start of a campaign to over-turn the regulations, and the Premier Ted Baillieu, should get the message.

"We've already negotiated in the private sector with the building companies all our enterprise bargaining agreements so why he wants to now set up a code that's going to interfere with all that and start to cut wages and conditions is beyond me," he said.

"The logic is beyond me."

The man charged with enforcing the regulations, Nigel Hadgkiss, says the code is designed to increase productivity, creating construction jobs.

"It is a little disappointing the unions have taken this stance against what is a move by Government to improve safety and bring about a better culture, better behaviours, on Victoria's building sites," he said.

He says companies who want Government work will have to take action against illegal strikes, including today's action.

"I've spoken to a lot of contractors who are taking a very strong approach to this they've warned their workers of the consequences if they do just walk off and take unlawful action," he said.

"A lot of contractors are extremely serious about wanting Government work and they're prepared to comply with these new guidelines to obtain that work."

Victoria's Finance Minister, Robert Clark, says union activity on building sites is costly and must be controlled.

"We believe that they should simply not be holding this industrial action because having productive and law abiding work places in Victoria, which is what these guidelines seek to achieve, is in the best interest of building workers because it ensures projects are affordable and building workers have got jobs they can go to."